If you stretch or ease in the rows, you will get cups in the quilt that will have to be quilted out. We ease in and stretch to fit clothing, not quilts. If you are constructing a quilt in rows, measure each row and make sure they are all the same before pinning together and sewing. If the little bit on the bottom is the problem, take that row off and measure the rest, then adjust that row to the same measurement and re-attach. I think the design is wonderful. You might just want to square up the top as it is now, and add a border of the white fabric all the way around.